In the periodical Der Nahverkehr [Local Transportation], No. 6/1996, pages 48 to 53, an innovative shell construction for a modular tram vehicle is described. In the four-part prototype vehicle which is shown in FIG. 2 of this reference a car body which is configured in the manner of a bridge (central module) is connected in an articulated fashion to two carriages which are each supported on a dual-axle set of running gear (dual-axle running gear modules). The prototype vehicle also has a car body which rests on a single-axle set of running gear (single-axle running gear module).
The lower articulated connections include vehicle joints which can move in a spherical fashion and are rigidly connected to the carriages by brackets. These lower joints, which are disclosed as an assembly in, for example, DE 101 39 970 A1, permit pivoting movements and in theory also pitching and rolling movements. The first embodiment of the above joints which is arranged between the central module and the two dual-axle running gear modules in the prototype vehicle only permit a pivoting movement about the vertical axis (z axis).
A second embodiment of the above joint which is arranged between the car body with the single-axle running gear module and the central module in the prototype also permits the vehicle to carry out a pitching movement about the transversal axis when traveling through a depression or over an elevation. With this second embodiment of the joints, the carriages are connected by way of a transversal connector which acts on a respective bracket of the two carriages.
In the modular vehicle explained above and also in other so-called multi-joint vehicles—see in this respect the periodical Railway Gazette 2003, pages 57 to 64, for example FIG. 4 “Dresden NGTD 6”, FIG. 6 “Citadis” and FIG. 7 “Cityrunner”—joints are therefore used which permit either only pivoting of the carriages about the vertical axis or pivoting and pitching of the carriages about the vertical axis or about the transversal axis. In certain track situations (such as in particular elevations in the track in bends or twists in the track) torsion may occur in the carriages resulting in high stresses on the structure of the carriages. Even if the carriages are dimensioned to cope with these high stresses, overloading and damage to the car body structures when traveling cannot be ruled out.
At least one embodiment the invention is therefore based on an object of embodying a large-capacity vehicle with the generic features in the simplest possible way such that overloading and damage to the car body structures are reliably avoided in all track situations.
An object may be achieved according to at least one embodiment of the invention in such a way that one of the articulated connections has a connecting element which is embodied and connected to two carriages in such a way that pivoting and rolling movements about the longitudinal axis of the vehicle are made possible. The connecting element can be embodied as a rigid connector rod and can be connected to the two carriages via ball and socket joints. Alternatively, it is possible to connect the connecting element as a twistable connector rod and to connect it to the two carriages via single-axle joints.
Since, according to at least one embodiment of the invention, one of the articulated connections permits a pivoting and rolling movement of the carriages, the wagon bodies are advantageously not subjected to any torsional stress which could cause damage.